What causes frying something to be crispy as opposed to boiling it?
In: 2042
It’s less simple than this, but boiling something in water helps the water get in everywhere.
Oil molecules are much bigger, so they can’t get into most places, and while boiling in oil does get the oil into it, you’re also getting the edges super hot (way over the 100°C water can handle), and driving the water out of them, making them crispy.
Oil has a much higher boiling point than water. When you drop food in hot oil, the water in the food boils, turns to steam, and leaves, leaving behind crispiness.
Water boils at 100degrees Celsius.
Your water in the pot is slightly below this temperature, so really, you are soaking your food in hot water.
This causes the food to absorb more water.
Absorbing more water tends to make things soft.
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Oil can go higher than 100 degrees Celsius.
The oil in the pot is above the boiling point of water, so it gives it’s heat to the food, and the water turns to steam and leaves the pot (as bubbles of water vapour->steam).
This causes the food to get drier, especially on the outside where it is touching the oil.
Becoming dry tends to make things harder, and the expanding bubbles of gas tend to leave little spaces behind, giving a ‘crisp’ feel, where it is rigid and hard, but breaks easily due to being thin/brittle.
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(If things get drier without this frying effect, then things tend to get cruchy or just solidly hard, like when you cook something for a long time in the oven. Consider baking bread, or the outside of a long-cooked roast, or overcooking biscuits/cookies. However, there are other ways to get things crispy than just frying, so other techniques can also get something baked in an oven to be crispy. However frying in oil tends to more easily make things crispy.)
Basically you are doing opposite things. Boiling is basically forcing water into the object while frying actually forces the water out.
Important to define “something”. Eggs get hard in boiling water. Frying unbattered cheese in oil makes it gooey.
Boiling in water breaks down fibers, making food soft. Frying in oil dehydrates and creates a crispy outer layer.
Hot Oil makes water go away(less water=crispy), hot water puts water in(more water =soggy).
Note, once ALL water is gone, oil can saturate and be extra nasty.
I’d like to add something here I don’t see yet. Water literally can’t get hotter than boiling point. (Well technically it can, but not on the stove in a normal way)
Once water gets to 100C, it turns into something else.
Oil actually gets hotter than 100C.
I highly suspect if water could get much higher, the same as oil does at frying temps, it would absolutely cook food like oil. It would also make the food more wet though. Not sure what that would be like.
Honestly I’d love to see food cooked in super heated water
Oils boil at a much higher temperature and don’t smoke/evaporate until around 450F degrees whereas water can only get up to 212F before turning to steam.
Water is what makes the things you’re talking about soft. When you boil something in water, the water gets inside everywhere. When we cook something in oil, we make the oil hotter than water boils at, so all of the water inside just boils and escapes as steam, leaving the thing very *unsoft*, aka crispy.
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